Organopolysiloxanes exhibiting nonlinear response

ABSTRACT

In a preferred embodiment this invention provides novel organopolysiloxanes which exhibit nonlinear optical response. 
     Illustrative of an invention organopolysiloxane is a polymer corresponding to the formula: ##STR1## wherein n is an integer of at least 5.

This invention was made with Government support under Contract NumberF49620-84-0110 awarded by the Department of Defense. The FederalGovernment has certain rights in this invention.

This is a division of Ser. No. 923,501, filed 10/27/86, now U.S. Pat.No. 4,801,659.

BACKGROUND OF THE INVENTION

It is known that organic compounds and polymeric materials with largedelocalized π-electron systems can exhibit nonlinear optical response,which in many cases is a much larger response than by inorganicsubstrates.

In addition, the properties of organic compounds and polymeric materialscan be varied to optimize other desirable properties, such as mechanicaland thermoxidative stability and high laser damage threshold, withpreservation of the electronic interactions responsible for nonlinearoptical effects.

Thin films of organic compounds or polymeric materials with large secondorder nonlinearities in combination with electronic circuitry havepotential as systems for laser modulation and deflection, informationcontrol in optical circuitry, and the like.

Other novel processes occurring through third order nonlinearity such asdegenerate four-wave mixing, whereby real-time processing of opticalfields occurs, have potential utility in such diverse fields as opticalcommunications and integrated circuit fabrication.

Of particular importance for conjugated organic systems is the fact thatthe origin of the nonlinear effects is the polarization of theπ-electron cloud as opposed to displacement or rearrangement of nuclearcoordinates found in inorganic materials.

Nonlinear optical properties of organic compounds and polymericmaterials was the subject of a symposium sponsored by the ACS divisionof Polymer Chemistry at the 18th meeting of the American ChemicalSociety, Sept. 1982. Papers presented at the meeting are published inACS Symposium Series 233, American Chemical Society, Washington, D.C.1983.

The above recited publications are incorporated herein by reference.

Prior art of interest with respect to the present invention arepublications relating to organopolysiloxane synthesis such as U.S. Pat.Nos. 2,716,128; 2,970,150; 3,159,662; 3,483,270; 3,694,478; 4,166,078;4,336,364; 4,370,365; 4,465,818; 4,472,563; and 4,578,494.

Of particular interest are publications which describeorganopolysiloxanes containing olefinically unsaturated substituents,such as U.S. Pat. Nos. 3,498,945; 3,932,555; 4,077,937; and 4,530,989.

Of related interest are publications which describe organopolysiloxaneshaving mesogenic side chain substituents, such as U.S. Pat. Nos.4,358,391 and 4,410,570.

There is continuing interest in the development of organopolysiloxanepolymers which exhibit exceptional properties for specializedapplications.

There is also a growing interest in the development of new nonlinearoptical organic media for prospective novel phenomena and devicesadapted for laser frequency conversion, information control in opticalcircuitry, light valves and optical switches. The potential utility oforganic materials with large second-order and third-order nonlinearitiesfor very high frequency application contrasts with the bandwidthlimitations of conventional inorganic electrooptic materials.

Accordingly, it is an object of this invention to provide novelorganopolysiloxane polymers.

It is another object of this invention to provide organopolysiloxanepolymers which exhibit nonlinear optical properties.

It is another object of this invention to provide novel nonlinearoptical organic media.

It is another object of this invention to provide optical devices havinga nonlinear optical component comprising a transparent solid medium of anovel organopolysiloxane.

It is a further object of this invention to provide novel compositionswhich are physical blends of an organopolysiloxane component and aliquid crystalline component.

Other objects and advantages of the present invention shall becomeapparent from the accompanying description and examples.

This patent application is related to copending patent application Ser.No. 923,507, filed Oct. 27, 1986.

DESCRIPTION OF THE INVENTION

One or more objects of the present invention are accomplished by theprovision of a polysiloxane which is characterized by a recurringstructural unit corresponding to the formula: ##STR2## where R is aninorganic substituent or an organic substituent containing between about1-12 carbon atoms; Z is a substituent selected from hydrogen andelectron-donating and electron-withdrawing substituents; and thepolysiloxane contains between about 2-2000 silicon atoms.

Illustrative of R inorganic substituents are chlorine, fluorine,bromine, nitro, amino, hydroxyl, thiolo, and the like.

Illustrative of R organic substituents are aliphatic, alicyclic andaromatic radicals such as methyl, trifluoromethyl, butyl, isobutyl,butenyl, ethoxyethyl, fluorohexyl, decyl, cyclopentyl, cyclohexenyl,phenyl, tolyl, benzyl, naphthyl, piperidyl, pyridyl, pyrazyl, and thelike.

In another embodiment this invention provides a polymer which ischaracterized by a recurring structural unit corresponding to theformula: ##STR3## where R¹ is a hydrocarbyl substituent containingbetween about 1-12 carbon atoms; n is an integer of at least 5; and Z'is an electron-donating or electron-withdrawing substituent.

When the polymer is a copolymer, preferably the above recurringstructural units comprise at least about 25 weight percent of thecopolymer. Illustrative of other recurring comonomeric units aredialkylsiloxyl, diarylsiloxyl, dialkylsilazanyl, oxyalkylene, and thelike. The copolymer can have alternating comonomeric units, or be in theform of block copolymers with block units of the type described in U.S.Pat. Nos. 3,483,270 and 4,586,997.

In another embodiment this invention provides a polymer which ischaracterized by a recurring structural unit corresponding to theformula: ##STR4## where R¹ is a hydrocarbyl substituent containingbetween about 1-12 carbon atoms; n is an integer of at least 5; X is anelectron-donating substituent; and Y is an electron-withdrawingsubstituent.

Illustrative of R¹ substituents are C₁ -C₄ alkyl groups and C₆ -C₁₀ arylgroups, such as methyl and phenyl radicals.

The term "electron-donating" as employed herein refers to organicsubstituents which contribute electron density to the π-electron systemwhen the conjugated electronic structure is polarized by the input ofelectromagnetic energy.

The term "electron-withdrawing" as employed herein refers toelectronegative organic substituents which attract electron density fromthe π-electron system when the conjugated electronic structure ispolarized by the input of electromagnetic energy.

Illustrative of electron-donating substituents as represented by Z, Z'or X in the above formulae are amino, alkylamino, dialkylamino,1-piperidyl, 1-piperazyl, 1-pyrrolidyl, acylamino, hydroxyl, thiolo,alkylthio, arylthio, acyloxy, halo, C₁ -C₃₀ hydrocarbyl, C₁ -C₃₀hydrocarbyloxy, C₁ -C₃₀ hydrocarbylthio, and the like.

Illustrative of electron-withdrawing substituents as represented by Z,Z'or Y in the above formulae are nitro, cyano, trifluoromethyl, acyl,carboxy, alkanoyloxy, aroyloxy, carboxamido, alkoxysulfonyl,aryloxysulfonyl, and the like.

In another embodiment this invention provides a thermoplastic polymerwhich is characterized by a recurring structural unit corresponding tothe formula: ##STR5## where R¹ is a hydrocarbyl substituent containingbetween about 1-12 carbon atoms; X' is a C₁ -C₃₀ alkyl, alkoxy oralkylthio substituent; Y' is a substituent selected from nitro, cyanoand trifluoromethyl groups; and the polymer contains between about5-2000 silicon atoms.

In another embodiment this invention provides a thermoplastic polymerwhich is characterized by a recurring structural unit corresponding tothe formula: ##STR6## where R¹ is a hydrocarbyl substituent containingbetween about 1-12 carbon atoms; R² and R³ are selected from hydrogenand C₁ -C₃₀ alkyl groups, and R² and R³ taken with the connectingnitrogen atom form a heterocyclic substituent; Y' is a substituentselected from nitro, cyano and trifluoromethyl groups; and the polymercontains between about 5-2000 silicon atoms.

Illustrative of a heterocyclic structure formed by R² and R³ takentogether with the connecting nitrogen atom is pyrrolidyl, imidazolidyl,oxazolidyl, thiazolidyl, and the like.

Illustrative of specific organopolysiloxanes of the present inventionare polymers represented by the following recurring structural units,wherein the polymers have a weight average molecular weight betweenabout 2000-100,000: ##STR7##

In another embodiment this invention provides a nonlinear optical mediumcomprising a noncentrosymmetric configuration of polymer moleculescharacterized by a recurring structural unit corresponding to theformula: ##STR8## where R¹ is a hydrocarbyl substituent containingbetween about 1-12 carbon atoms; n is an integer of at least 5; and Z'is an electron-donating or electron-withdrawing substituent.

Depending on the nature of the Z' substituents in the above polysiloxaneformula, the nonlinear optical medium can exhibit a second ordernonlinear optical response. Illustrative of a second order nonlinearoptical response is an optical susceptibility χ.sup.(2) of about 1×10⁻⁷esu at 1.91 μm, and a Miller's Delta of about one square meter/coulomb.

The term "Miller's delta" as employed herein with respect to secondharmonic generation (SHG) is defined by an equation as elaborated byGarito et al in Chapter 1, "Molecular Optics:Nonlinear OpticalProperties Of Organic And Polymeric Crystals"; ACS Symposium Series 233(1983).

The quantity "delta"(δ) is defined by the equation: ##EQU1## where termssuch as χ_(ii).sup.(1) are representative linear susceptibilitycomponents, and d_(ijk), the second harmonic coefficient, is definedthrough ##EQU2##

The Miller's delta (10⁻² m² /c at 1.06 μm) of various nonlinear opticalcrystalline substrates are illustrated by KDP(3.5), LiNbO₃ (7.5),GaAs(1.8) and 2-methyl-4-nitroaniline(160).

In another embodiment this invention provides a nonlinear optical mediumcomprising a centrosymmetric configuration of polymer moleculescharacterized by a recurring structural unit corresponding to theformula: ##STR9## where R¹ is a hydrocarbyl substituent containingbetween about 1-12 carbon atoms; n is an integer of at least 5; and Z'is an electron-donating or electron-withdrawing substituent.

A nonlinear optical medium with a centrosymmetric molecularconfiguration as defined above exhibits a third order nonlinear opticalresponse. Illustrative of a third order nonlinear optical response is anoptical susceptibility χ.sup.(3) of about 1×10⁻¹² esu at 1.91 μm.

In another embodiment this invention provides an optical device, e.g.,an electrooptic light modulator, with an organic nonlinear opticalcomponent comprising a transparent solid medium of a polymer which ischaracterized by a recurring structural unit corresponding to theformula: ##STR10## where R¹ is a hydrocarbyl substituent containingbetween about 1-12 carbon atoms; n is an integer of at least 5; and Z'is an electron-donating or electron-withdrawing substituent.

The term "transparent" as employed herein refers to an optical mediumwhich is transparent or light transmitting with respect to incidentfundamental light frequencies and created light frequencies. In anonlinear optical device, a present invention nonlinear optical mediumis transparent to both the incident and exit light frequencies.

Synthesis Of Organopolysiloxanes

A present invention organopolysiloxane polymer can be prepared by thereaction of a selected organosilicon structure having a silicon-bondedhydrogen atom with a selected acetylenic compound in the presence of ahydrosilylation catalyst: ##STR11##

The use of a platinum catalyst to promote the condensation of a silanichydrogen-bonded siloxane with an unsaturated compound is described inU.S. Pat. Nos. 2,970,150; 3,159,662; 4,077,937; and 4,530,989.

Organohydrogenpolysiloxanes are prepared in a general procedure asdescribed in U.S. Pat. No. 4,370,365 by the hydrolysis of one or moreorganohalosilanes having silicon-bonded hydrogen such asmethyldichlorosilane, followed by condensation of the hydrolysisproduct.

The acetylenic starting material utilized for preparation of the presentorganopolysiloxanes can be synthesized by conventional procedures, suchas by employing benzoin or cinnamic acid type of intermediates in themanner described in Organic Synthesis, coll. vol. III, 786 (1955) andcoll. vol. IV, 857 (1963).

The following flow diagram illustrates a reaction scheme for synthesisof an acetylene monomer: ##STR12##

Blends of Polysiloxane And Liquid Crystalline Components

In another embodiment this invention provides a composition which is ablend of components comprising:

(a) a polysiloxane component which is characterized by a recurringstructural unit corresponding to the formula: ##STR13## where R is aninorganic substituent or an organic substituent containing between about1-12 carbon atoms; Z is a substituent selected from hydrogen and anelectron-donating and electron-withdrawing substituents; and thepolysiloxane contains between about 2-2000 silicon atoms; and

(b) a liquid crystalline component.

In another embodiment this invention provides a thermoplasticcomposition which is a blend of components comprising:

(a) a polysiloxane component which is characterized by a recurringstructural unit corresponding to the formula: ##STR14## where R¹ is ahydrocarbyl substituent containing between about 1-12 carbon atoms; n isan integer of at least 5; and Z' is an electron-donating orelectron-withdrawing substituent; and

(b) a liquid crystalline component.

Characteristic of an invention composition is a blend which has a glasstransition temperature above about 40° C., and exhibits nonlinearoptical response.

The proportion of polysiloxane component in the composition can varybetween about 10-90 weight percent of the total weight of components.

The liquid crystalline component can be a low molecular weight compoundor an oligomeric or polymeric liquid crystal.

A liquid crystalline polymer component can be either a main chain orside chain liquid crystalline polymer. Illustrative of a liquidcrystalline polymer component is a thermotropic liquid crystallinepolymer containing recurring benzimidazole, benzthiazole or benzoxazolestructures.

The polysiloxane component and/or the liquid crystalline component of aninvention composition blend can exhibit nonlinear optical response.

An invention composition can be prepared by physically blending the twocomponents, such as when both of the components are solids at ambienttemperature. A solid admixture can be homogenized further by melting thephysical blend, and then cooling to solidify the melt phase in the formof an organic alloy.

An invention composition also can be prepared by dissolving thepolysiloxane and liquid crystalline components in an organic solvent andthen removing the solvent medium to provide the composition blend.

An organic solvent solution of a composition can be utilized to castfilms or to coat optical substrates. Suitable organic solvents includebenzene, toluene, chloroform, tetrahydrofuran, N,N-dimethylformamide,N,N-dimethylacetamide, dimethylsulfoxide, N-methyl-2-pyrrolidone, andthe like.

A spinning dope of an invention composition can be prepared and employedfor the production of fibers. An invention composition in a molten statecan be employed for molding or extruding of shaped articles.

In another embodiment this invention provides a composition which is ablend of components comprising:

(a) a polysiloxane component which is characterized by a recurringstructural unit corresponding to the formula: ##STR15## where R¹ is ahydrocarbyl substituent containing between about 1-12 carbon atoms; n isan integer of at least 5; X is an electron-donating substituent; and Yis an electron-withdrawing substituent; and

(b) a liquid crystalline polymer component which is characterized by arecurring wholly aromatic structural unit corresponding to the formula:

    --Ar-X-Ar--

where X is a divalent radical selected from estero, amido, azomethino,azo, azoxy, etheno and ethyno groups, and Ar is a divalent aromaticradical selected from phenylene, naphthylene and diphenylene groups, andaromatic radicals corresponding to the formula: ##STR16## where Y is acarbonyl, sulfono, oxy or thio group.

Illustrative of a wholly aromatic liquid crystalline polymer componentis a copolymer of p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid.

The term "wholly aromatic" as employed herein refers to a linearthermotropic liquid crystalline polymer in which each recurringmonomeric unit contributes at least one aromatic nucleus to the polymerbackbone.

The term "thermotropic" as employed herein refers to polymers which areliquid crystalline (i.e., anisotropic) in the melt phase.

Wholly aromatic thermotropic liquid crystalline polymers are disclosedin U.S. Pat. Nos. 3,526,611; 3,991,013; 4,048,148; 4,057,597; 4,066,620;4,067,852; 4,075,262; 4,083,829; 4,107,143; 4,118,372; 4,122,070;4,130,545; 4,146,702; 4,153,779; 4,156,070; 4,159,365; 4,161,470;4,169,933; 4,181,792; 4,184,996; 4,188,476; 4,219,461; 4,224,433;4,230,817; 4,238,598; 4,238,599; 4,256,624; 4,332,759; and 4,381,389;incorporated herein by reference.

In a further embodiment this invention provides a thermoplasticcomposition which is a blend of components comprising:

(a) a polysiloxane component which is characterized by a recurringstructural unit corresponding to the formula: ##STR17## where R¹ is ahydrocarbyl substituent containing between about 1-12 carbon atoms; n isan integer of at least 5; X is an electron-donating substituent; and Yis an electron-withdrawing substituent; and

(b) a side chain liquid crystalline polymer component which ischaracterized by a recurring structural unit corresponding to theformula: ##STR18## where P is a polymer main chain unit, S is a flexiblespacer group having a linear chain length of between about 0-20 atoms, Mis a pendant mesogen, and where the pendant mesogens comprise at leastabout 10 weight percent of the polymer and the polymer has a glasstransition temperature above about 60° C.

Side chain liquid crystalline polymers are disclosed in U.S. Pat. Nos.4,293,435; 4,358,391; and 4,410,570; incorporated herein by reference.

Other literature describing side chain liquid crystalline polymersinclude J. Polym. Sci., 19, 1427 (1981); Eur. Polym. J., 18,651 (1982);Polymer, 26, 615 (1985); incorporated herein by reference.

Side chain liquid crystalline polymers exhibiting nonlinear opticalresponse are disclosed in copending patent application Ser. No. 822,090,filed Jan. 24, 1986; incorporated herein by reference.

Liquid crystalline polymer technology is reviewed in "Polymeric LiquidCrystals", (Plenum Publishing Corporation, N.Y., 1985), and in "PolymerLiquid Crystals" (Academic Press, N.Y., 1982); incorporated herein byreference.

A present invention composition blend of polysiloxane and liquidcrystalline components can be shaped into a centrosymmetric ornoncentrosymmetric optical medium such as a transparent film or coating,and employed as an organic nonlinear optical unit in a light modulatordevice, e.g., a laser frequency converter device.

Nonlinear Optical Properties

The fundamental concepts of nonlinear optics and their relationship tochemical structures can be expressed in terms of dipolar approximationwith respect to the polarization induced in an atom or molecule by anexternal field.

As summarized in the ACS Symposium Series 233 (1983) listed hereinabovein the Background Of The Invention section, the fundamental equation (1)below describes the change in dipole moment between the ground stateμ_(g) and an excited state μ_(e) expressed as a power series of theelectric field E which occurs upon interaction of such a field, as inthe electric component of electromagnetic radiation, with a singlemolecule. The coefficient α is the familiar linear polarizability, β andγ are the quadratic and cubic hyperpolarizabilities, respectively. Thecoefficients for these hyperpolarizabilities are tensor quantities andtherefore highly symmetry dependent. Odd order coefficients arenonvanishing for all structures on the molecular and unit cell level.The even order coefficients such as β are zero for those structureshaving a center of inversion symmetry on the molecular and/or unit celllevel.

Equation (2) is identical with (1) except that it describes amacroscopic polarization, such as that arising from an array ofmolecules in a liquid crystalline domain:

    Δμ=μ.sub.e -μ.sub.g =αE+βEE+γEEE+(1)

    P=P.sub.O +χ.sup.(1) E+χ.sup.(2) EE+χ.sup.(3) EEE+(2)

Light waves passing through an array of molecules can interact with themto produce new waves. This interaction may be interpreted as resultingfrom a nonlinearity of the induced polymerization. For wholly opticalprocesses such interaction occurs most efficiently when certain phasematching conditions are met, requiring identical propagation speeds ofthe fundamental wave and the harmonic wave. Birefringent crystals oftenpossess propagation directions in which the refractive index for thefundamental ω and the second harmonic 2ω are identical so thatdispersion may be overcome.

The term "phase matching" as employed herein refers to an effect in anonlinear optical medium in which a harmonic wave is propagated with thesame effective refractive index as the incident fundamental light wave.Efficient second harmonic generation requires a nonlinear optical mediumto possess propagation directions in which the optical mediumbirefringence cancels the natural dispersion, i.e., the opticaltransmission of fundamental and second harmonic frequencies is phasematched in the medium. The phase matching can provide a high conversionpercentage of the incident light to the second harmonic wave.

For the general case of parametric wave mixing, the phase matchingcondition is expressed by the relationship:

    n.sub.1 ω.sub.1 +n.sub.2 ω.sub.2 =n.sub.3 ω.sub.3

where n₁ and n₂ are the indexes of refraction for the incidentfundamental radiation, n₃ is the index of refraction for the createdradiation, ω₁ and ω₂ are the frequencies of the incident fundamentalradiation and ω₃ is the frequency of the created radiation. Moreparticularly, for second harmonic generation, wherein ω₁ and ω₂ are thesame frequency ω, and ω₃ is the created second harmonic frequency 2ω,the phase matching condition is expressed by the relationship:

    n.sub.ω =n.sub.2ω

where n.sub.ω and n₂ω are indexes of refraction for the incidentfundamental and created second harmonic light waves, respectively. Moredetailed theoretical aspects are described in "Quantum Electronics" byA. Yariv, chapters 16-17 (Wiley and Sons, N.Y., 1975).

A present invention organopolysiloxane alone or in admixture with aliquid crystalline polymer typically is optically transparent andexhibits hyperpolarization tensor properties such as second harmonic andthird harmonic generation, and the linear electrooptic (Pockels) effect.For second harmonic generation, the bulk phase of an organopolysiloxaneor an admixture with a liquid crystalline polymer whether liquid orsolid does not possess a real or orientational average inversion center.The substrate is a macroscopic noncentrosymmetric structure.

Harmonic generation measurements relative to quartz can be performed toestablish the value of second order and third order nonlinearsusceptibility of the optically clear substrates.

In the case of macroscopic nonlinear optical substrates that arecomposed of noncentrosymmetric sites on the molecular and domain level,the macroscopic second order nonlinear optical response χ.sup.(2) iscomprised of the corresponding molecular nonlinear optical response β.In the rigid lattice gas approximation, the macroscopic susceptibilityχ.sup.(2) is expressed by the following relationship:

    χ.sub.IJK (-ω.sub.3 ; ω.sub.1,ω.sub.2)=Nf.spsp.ω.sbsp.3f.spsp.ω.sbsp.2f.spsp.ω.sbsp.1<β.sub.ijk (-ω.sub.3 ; ω.sub.1,ω.sub.2)>

wherein N is the number of sites per unit volume, f represent smalllocal field correlations, β_(ijk) is averaged over the unit cell, ω₃ isthe frequency of the created optical wave, and ω₁ and ω₂ are thefrequencies of the incident fundamental optical waves.

These theoretical considerations are elaborated by Garito et al inchapter 1 of the ACS Symposium Series 233 (1983); and by Lipscomb et alin J. Chem., Phys., 75, 1509 (1981), incorporated by reference. See alsoLalama et al, Phys. Rev., A20, 1179 (1979); and Garito et al, Mol.Cryst. and Liq. Cryst., 106, 219 (1984); incorporated by reference.

The microscopic response, or electronic susceptibility β, and itsfrequency dependence or dispersion, can be experimentally determined byelectric field induced second harmonic generation (DCSHG) measurementsof liquid solutions or gases as described in "Dispersion Of TheNonlinear Second Order Optical Susceptibility Of Organic Systems",Physical Review B, 28 (No. 12), 6766 (1983) by Garito et al, and theMolecular Crystals and Liquid Crystals publication cited above; or bysolvatochromism measurements as described in "Nonlinear Optics: AMolecular Basis For Electronic Susceptibility", by Buckley et al, A.C.S.National Meeting, New York, N.Y., Apr. 17, 1986; published in A.C.S.Symposium Series.

In the measurements, the created frequency ω₃ is the second harmonicfrequency designated by 2ω, and the fundamental frequencies ω₁ and ω₂are the same frequency designated by ω. An applied DC field removes thenatural center of inversion symmetry of the solution, and the secondharmonic signal is measured using the wedge Maker fringe method. Themeasured polarization at the second harmonic frequency 2ω yields theeffective second harmonic susceptibility of the liquid solution an thusthe microscopic susceptibility β for the molecule.

External Field-Induced Molecular Orientation

In the nonlinear optical media described hereinabove, thecentrosymmetric or noncentrosymmetric configuration of polysiloxanemolecules alone or in association with liquid crystalline molecules canbe external field-induced.

The term "external field" as employed herein refers to an electric,magnetic or mechanical stress field which is applied to a substrate ofmobile organic molecules, to induce dipolar alignment of the moleculesparallel to the field.

In a melt phase blend of a present invention polysiloxane in admixturewith a liquid crystalline component, both types of molecules will alignunder the influence of an electric or magnetic field. The degree oforientation is determined by the orientational order parameter.

For both nematic and smectic mesophases, the parameter is defined interms of a director which is a vector parallel to the molecular longaxis (and perpendicular to the plane of molecular layering in the caseof the smectic mesophase).

If theta is defined as the angle between the director and a chosen axis,then the orientational order parameter is defined as the average overall molecules of the second Legendre polynomial. The parameter rangesfrom -0.5 to 1.0 (1.0 corresponds to perfect uniaxial alignment along agiven axis. 0.0 corresponds to random orientation, and -0.5 correspondsto random orientation confined in a plane perpendicular to a givenaxis).

The order parameter thus defined does not distinguish between paralleland antiparallel alignment. Thus, a sample of asymmetric rod-likemolecules would have an order parameter of 1.0 for both the case inwhich the molecules are colinear and all pointed in the same direction,and the case in which the molecules are colinear and form antiparallelpairs.

The application of an orienting external field to an array of nematicliquid crystal molecules results in an order parameter of approximately0.65. Deviations from ideal order are due to nematic fluctuations on amicron length scale which accommodate characteristic defects. Thesefluctuations may be dynamic for small molecule liquid crystals or frozenfor polymeric liquid crystals.

Smectic liquid crystals may be aligned by application of an orientingexternal field, with a resulting order parameter exceeding 0.9. Unlikethe nematic phase, characteristic defects are removed upon aligning thesmectic phase and thereby forming a single liquid crystal phase. Suchphases are known as monodomains and, because there are no defects, areoptically clear.

For both the nematic and smectic mesophases, application of a DCelectric field produces orientation by torque due to the interaction ofthe applied electric field and the net molecular dipole moment. Themolecular dipole moment is due to both the permanent dipole moment(i.e., the separation of fixed positive and negative charge) and theinduced dipole moment (i.e., the separation of positive and negativecharge by the applied field).

The torque which results by the application of a DC electric fieldnormally would only produce very slight alignment even for high dipolarand polarizable molecules at room temperature. The alignment torque isnegligible in comparison with the disordering effect of thermallyinduced rotation (i.e., the Boltzman distribution of rotationaleigenstates at room temperature). However, due to the uniqueassociations developed by liquid crystalline molecules throughintermolecular forces, long range orientational order on a micron lengthscale is present. Under these conditions, bulk orientation of the sampleby application of aligning fields exceeding a few volts/cm can producethe degrees of alignment indicated above.

Application of an AC electric field also can induce bulk alignment. Inthis case, orienting torque occurs solely due to the interaction of theapplied AC field and the induced dipole moment. Typically, AC fieldstrengths exceeding 1 kV/cm at a frequency exceeding 60 KHz are employedfor the nematic phase. At these frequencies, rotational motion ofaligned nematic regions is not sufficient to follow the field. As adirect result, torque due to the interaction of the applied field andany permanent dipole moment over time averages to zero. However,electronically induced polarization is a very rapid process so that theinduced dipole moment changes direction depending upon the direction ofthe applied field resulting in a net torque.

Application of a magnetic field also can effect alignment. Organicmolecules do not possess a permanent magnetic dipole moment. In a manneranalogous to AC electric field, a magnetic field can induce a netmagnetic dipole moment. Torque results from the interaction of theinduced dipole moment and the external magnetic field. Magnetic fieldstrengths exceeding 10 Kgauss are sufficient to induce alignment for anematic phase or smectic phase.

Alignment of nematics by electric or magnetic fields are accomplishedsimply by application of the field to the nematic material. Alignment ofthe smectic phase is more difficult due to a higher viscosity whichdecreases rotational freedom. Formation of aligned smectic monodomainscan be achieved by orienting a material in the nematic phase, andcooling the material into the smectic phase while maintaining thealigning field. For materials which have only smectic and isotropicphases and which lack a nematic phase, alignment can be accomplished inthe smectic phase at an elevated temperature near the smectic toisotropic transition temperature, e.g., sufficiently close to thetransition temperature so that the medium may contain smectic domains inan isotropic fluid.

Mechanical stress induced alignment is applicable to both the smecticand nematic mesophases. Strong aligning mechanical stress propagatesthroughout a solid liquid crystalline material due to the naturaltendency of these media to self align. Specific mechanical stressmethods include stretching a thin film, or coating a composition surfacewith an aligning polymer such as nylon, polyethylene terephthalate,polyvinyl alcohol, and the like. Physical methods (e.g., stretching)rely upon the rigid and geometrically asymmetric character of certainmolecules to induce bulk orientation. Chemical methods (e.g., coatingthe surface with an aligning polymer) rely upon strong intermolecularinteractions to induce surface orientation. All of the methods describedabove to produce oriented materials generally apply to small moleculeand polymeric liquid crystals and polysiloxanes. For polymers whichpossess a glass transition, the mobile phase of aligned molecules can befrozen by rapid cooling below the glass transition temperature.

In melt phase blends of polysiloxane and liquid crystalline components,the degree and direction of polysiloxane molecular alignment in anexternal field is influenced directionally by the axial configuration ofthe liquid crystalline molecules.

Publications relating to external field-induced molecular orientationinclude The Physics of Liquid Crystals, P. G. deGennes, p. 95-97, OxfordUniversity Press, 1974; J. Stamatoff et al, "X-Ray DiffractionIntensities of a Smectic-A Liquid Crystal", Phys. Rev. Letters, 44,1509-1512, 1980; J. S. Patel et al, "A Reliable Method of Alignment forSmectic Liquid Crystals", Ferroelectrics, 59, 137-144, 1984; J. Cognard,"Alignment of Nematic Liquid Crystals and Their Mixtures", Mol. Cryst.Liq. Cryst.:Suppl., 1982; incorporated herein by reference.

The following examples are further illustrative of the presentinvention. The components and specific ingredients are presented asbeing typical, and various modifications can be derived in view of theforegoing disclosure within the scope of the invention.

EXAMPLE I

This Example illustrates the preparation of polymethylhydrosiloxane inaccordance with the procedure described in the Journal of HighResolution Chromatography and Chromatography Communications, 8, 516(1985).

Acetonitrile (2.5 ml) and water (2.5 ml) are added tomethyldiethoxysilane (0.033 mole) and dimethyldimethoxysilane (0.033mole) and the resulting solution is stirred for 1 hour. A solution ofbenzenesulfonic acid (0.1 M in H₂ O) is added and the mixture is stirredunder an argon purge for 26 hours. An excess of hexamethyldisilazane isadded and the solution is stirred at 20° C. for 15 minutes. Thetemperature then is raised to 80° C. for 2 hours to remove the residualdisilazane.

The encapped polymer is dissolved in dichloromethane and precipitatedwith methanol. The fractionation process is repeated twice, and thedissolved polymer is filtered through a millipore filter. A colorlessviscous oil remains after solvent evaporation, which has a weightaverage molecular weight of about 20,000.

EXAMPLE II

This Example illustrates the preparation of 1,2-diphenylethylenecompounds.

A.

To a stirred solution of 21.6 grams (0.1 mole) of 4-nitrobenzyl bromidein 500 ml of toluene is added in several portions 26.2 grams (0.1 mole)of triphenyl phosphine. The solution is heated at reflux for one hour,during which time the Wittig salt forms and precipitates from solution.The reaction mixture is cooled to room temperature, and the saltprecipitate is filtered from the toluene, washed with fresh toluene toremove any unreacted triphenyl phosphine and 4-nitrobenzyl bromide, andthen dried in an open dish.

B.

To a stirred solution of 44 grams of dry potassium carbonate in 500 mlof acetone is added 12.2 grams (0.1 mole) of 4-hydroxybenzaldehyde, andthe resultant mixture is heated to reflux temperature. After a refluxingperiod of a half hour, 17.4 grams of n-octyl bromide (0.09 mole) isadded to the mixture. The reaction medium is maintained at reflux forabout 20 hours, then the product mixture is cooled to room temperatureand potassium salt precipitate is filtered off. The acetone is removedby vacuum distillation, and a residual crude product is recovered.4-octyloxybenzaldehyde product is purified by distillation under vacuum(bp. 140° C. at 0.1 torr).

C.

To a stirred solution of 30 grams (0.063 mole) of Wittig salt asprepared in step A in 200 ml of dry toluene in a 500 ml flask fittedwith a rubber septum, reflux condenser and addition funnel is added 39ml of n-butyl lithium (0.63 mole) in hexane (1.6 M) through the septumusing a syringe. The red solution is refluxed for a half hour, and then14.75 grams of 4-octyloxybenzaldehyde (0.63 mole) as prepared in step Bin 50 ml of toluene is added dropwise through the addition funnel.

The mixture is cooled to room temperature and dissolved in ether (500ml). The resultant solution is extracted four times with distilled waterto remove the triphenyl phosphine oxide and lithium bromide salts. Theether solution is dried over anhydrous magnesium sulfate, and after themagnesium sulfate is separated by filtration the ether is removed byvacuum distillation to yield a residual crude product. The4-octyloxy-4'-nitrodiphenylethylene product is purified byrecrystallization from absolute ethanol.

D.

A reaction flask equipped with a stirrer and condenser is charged with200 ml of N,N-dimethylformamide and 11.2 grams (0.1 mole) of potassiumt-butoxide. The flask is sealed and flushed with argon. A 14.6 gramquantity of n-octyl thiol is added to the solution via syringe. Thereaction medium is heated at 60° C. for a half hour, then 12.1 grams of4-fluorobenzaldehyde are added via syringe. The mixture is stirred at60° C. for 4 hours, and after cooling 300 ml of water are added and theresultant aqueous solution is extracted three times with hexane. Thehexane extracts are combined and dried over anhydrous magnesium sulfate.The magnesium sulfate and hexane are removed to yield a residual oil.The crude 4-octylthiobenzaldehyde product is purified by vacuumdistillation (b.p. 149° C. at 0.6 torr).

E.

Following the procedure of step C, 15.75 grams of4-octylthiobenzaldehyde is reacted with 30 grams of Wittig salt to yield4-octylthio-4'-nitrodiphenylethylene product.

EXAMPLE III

This Example illustrates the preparation of diphenylacetylene compounds.

A.

To a stirred mixture of 90 grams (0.334 mole) of4-N,N-dimethylamino-4'-nitro-1,2-diphenylethylene in 3 liters of1,2,3-trichloropropane solvent in a 5 liter three-neck round bottomflask are added 59.0 grams (0.369 mole) of bromine in 200 ml of1,2,3-trichloropropane over a period of about a half hour. The solutionis stirred for one hour, and then 4.1 grams (0.05 mole) of cyclohexeneis added to react with any residual bromine. The solvent is removed invacuo and the residual semi-solid product is washed with hexane toremove any remaining solvent and dibromocyclohexane.

The semi-solid product is dissolved in 3 liters of absolute ethanol, andthe solution is charged to a three-neck round bottom flask fitted with areflux condenser, mechanical stirrer, and 500 ml addition funnel.

A 150 gram (1.336 moles) quantity of potassium t-butoxide is dissolvedinto 350 ml of absolute ethanol, and the solution is added slowly fromthe addition funnel to the refluxing solution of dibromodiphenylethanederivative, and the solution is refluxed for a half hour after theaddition is completed. When the reaction medium is basic to pH paper,the reaction is stopped. The solution is hot filtered and allowed tocool. Solids are separated from the ethanol solution by filtration, andthe ethanol solvent is removed in vacuo to yield a residual solidproduct. The 4-N,N-dimethylamino-4'-nitrodiphenylacetylene product isrecrystallized from ethyl acetate.

B.

Employing the same procedure, 4-octylthio-4'-nitro-1,2-diphenylethyleneis converted to 4-octylthio-4'-nitrodiphenylacetylene.

C.

Employing the same procedure,4-hexadecyloxy-4'-nitro-1,2-diphenylethylene is converted to4-hexadecyloxy-4'-nitrodiphenylacetylene.

D.

Employing the same procedure, 4-ethoxy-4'-cyano-1,2-diphenylethylene isconverted to 4-ethoxy-4'-cyanodiphenylacetylene.

EXAMPLE IV

This Example illustrates the production of organopolysiloxane polymersin accordance with the present invention. ##STR19##

A 6.0 gram quantity of diphenylacetylene (33.7 mmoles) is dissolved in45 ml of dry toluene in a 100 ml round bottomed flask equipped with astirrer, and then 2 grams of polymethylhydrosiloxane (33.3 mmoles ofreactive sites) is added. The reaction medium is heated to reflux todegass the flask with vapors. The flask is then stoppered with a syringeseptum, and maintained at 60° C. with stirring.

One drop of chloroplatinic acid solution (0.5 M platinum IV chloride indry 2-propanol) is introduced to the stirring solution via a 25microliter syringe (about 3-4 microliters). The reaction mixture isstirred for 16 hours at 60° C.

After cooling the product solution is filtered through a fluted filterpaper into an excess of ice-cold methanol (about 1 liter). The crudepolymer product is a viscous off-white precipitate which graduallycoagulates on standing in the methanol medium. The methanol is decanted,and the residual crude polymer product is redissolved in toluene and themethanol precipitation procedure is repeated. The recovered polymer isdried in a vacuum oven at 120° C. for one hour. The final product is aclear hard glassy polymer which readily subdivides into small pieces.##STR20##

Employing the same procedure, 0.5 gram (1.88 mmoles) of 4,N,N-dimethylamino-4'-nitrodiphenylacetylene is reacted with 0.11 gram ofpolymethylhydrosiloxane (1.83 hydrogen equivalents).

After two precipitations in methanol solvent as described in section Aabove, the resultant viscous red polymer is dissolved indichloromethane. The solvent is allowed to evaporate off at roomtemperature, and the resultant polymer product is dried in a 120° C.vacuum oven. ##STR21##

Following the same procedure, 1.0 gram (3.76 mmoles) of4-N,N-dimethylamino-4'-nitrodiphenylacetylene and 0.72 gram (2.8 mmoles)of a 50:50 copolymer of methylphenylsiloxane and methylhydrosiloxane arereacted to form the above illustrated organopolysiloxane polymer.##STR22##

Following the same procedure, 1.0 gram (3.76 mmoles) of4-N,N-dimethylamino-4'-nitrodiphenylacetylene and 0.45 gram (3.36mmoles) of a copolymer of dimethylsiloxane and methylhydrosiloxane arereacted to form the above illustrated organopolysiloxane polymer.

The polymer precipitations are conducted in a hexane solvent, becausethe polymer is soluble in the methanol solvent employed in the abovepreparations. ##STR23##

Following the same procedure, 1.0 gram (3.76 mmoles) of4-N,N-dimethylamino-4'-nitrodiphenylacetylene and 0.41 gram (3.37mmoles) of polyphenylhydrosiloxane are reacted to form the aboveillustrated organopolysiloxane polymer.

EXAMPLE V

This Example illustrates the preparation of a thin substrate ofpolysiloxane polymer with a macroscopic noncentrosymmetric molecularorientation in accordance with the present invention.

A polysiloxane polymer prepared in accordance with Example I iscompression molded to form a film of about 500 micron thickness.

The molding is accomplished in a 30 Ton press (Wabash Metal Products,Inc. Model #30-1010-2TMX) with programmed heating and cooling, andadjustable pressure. The platen temperature is set at 200° C. Thepolymer in particulate form is placed between two Kapton (DuPontpolyimide) sheets and positioned between the two platens. The platensare closed and 6 tons pressure is applied for 2 minutes. The platens arethen cooled, the pressure is released, and the film sample is retrievedfrom the press.

X-ray diffraction patterns from this transparent film sample, recordedby using nickel filtered CuK.sub.α radiation and flat plate photographictechniques, indicate a random orientation of polymer molecule axes. Thefilm exhibits a third order nonlinear optical response.

Molecular alignment of the polymer molecule axes is achieved in thefollowing manner. The film sample is sandwiched between two Kapton filmsof 0.002 inch thickness which in turn are sandwiched between two metalplates of 0.25 inch thickness, each having a ground flat surface and arod attached to one side which serves as a contact for application ofvoltage in the alignment procedure. The sub-assembly is covered on topand bottom with a double layer of Kapton sheets of 0.002 inch thicknessand providing a 0.004 inch electrical insulating layer against eachplaten.

The whole assembly is placed between the platens of the press previouslyemployed for preparing the unoriented precursor film sample. The platensare preheated to 200° C., then closed and a pressure of 6 tons isapplied. Wires from a DC power supply are attached to the rods of theelectrode plates and a voltage of 700 V is applied for two hours whilemaintaining temperature and pressure.

The press is cooled while pressure and voltage are maintained, then thevoltage is reduced to zero and the pressure released. The molecularlyaligned film sample is retrieved from the mold, and X-ray diffractionpatterns are recorded with nickel filtered CuK.sub.α radiation andwide-angle photographic flat plate techniques. Orientation functions aredetermined utilizing a polar table and a microdensitometer interfacedwith a LeCray computer.

The data demonstrate that the molecular alignment process results in arotation of essentially all of the molecular axes of the polymermolecules out of the film plane into a direction parallel to that of theexternal field. This type of molecularly aligned polysiloxane film isnoncentrosymmetric and can function as a second-orderharmonic-generating nonlinear optical medium for a high intensity lightfield to which the medium is optically clear, e.g., as the nonlinearoptical component in a laser frequency converter device, with aχ.sup.(2) susceptibility of at least about 1×10⁻⁷ esu and a Miller'sdelta of at least about one square meter/coulomb.

EXAMPLE VI

This Example illustrates the preparation ofpoly[6-(4-nitrobiphenyloxy)hexyl methacrylate]. ##STR24##

A. 4-Hydroxy-4'-nitrobiphenyl (1) 4-benzoyloxybiphenyl

To 500 ml of pyridine in a 1000 ml three-neck flask is added 170 g of4-hydroxybiphenyl. The mixture is cooled to 10° C., and 155 g of benzoylchloride is added dropwise while keeping the mixture temperature below20° C. After complete addition, the mixture is heated gradually toreflux and maintained at this temperature for 30 minutes. The reactionmixture is then cooled to room temperature.

The solidified product subsequently is admixed with 250 ml HCl and 250ml water, then additional HCl and water are added and the slurry ismixed thoroughly in a blender. The particulate solid is filtered, washedwith water to a neutral pH, and air-dried overnight. The crude productis recrystallized from n-butanol, mp 149°-150° C.

(2) 4-benzoyloxy-4'-nitrobiphenyl

4-Benzoyloxybiphenol (40 g) is mixed with 310 ml of glacial acetic acidand heated to 85° C. Fuming nitric acid (100 ml) is added slowly whilemaintaining the reaction medium temperature between 85°-90° C. Aftercomplete addition, the reaction is cooled to room temperature.

The resultant solid is filtered and washed with water and methanol. Thecrude product is recrystallized from glacial acetic acid, mp 211°-214°C.

(3) 4-Hydroxy-4'-nitrobiphenyl

4-Benzoxyloxy-4'-nitrobiphenyl (60 g) is mixed with 300 ml of ethanoland heated to reflux. A solution of 40 g KOH in 100 ml of water is addeddropwise at reflux. After complete addition, the mixture is refluxed 30minutes and cooled overnight. The resultant blue crystalline potassiumsalt is filtered and dried.

The dried salt is dissolved in a minimum amount of boiling water, and a50/50 HCl/water solution is added until an acidic pH is obtained. Thecrude yellow product is filtered and washed with water until neutral,and then recrystallized from ethanol, mp 203°-204° C.

B. 4-(6-Hydroxyhexyloxy)-4'-nitrobiphenyl

To 400 ml of ethanol is added 21.5 g of 4-hydroxy-4'-nitrobiphenyl andthe mixture is heated to reflux. A solution of 7.1 g of KOH in 30 ml ofwater is added dropwise at reflux temperature. After complete addition,a 21.7 g quantity of 6-bromohexanol is added, and the reaction medium isrefluxed about 15 hours. Then the reaction medium is cooled and theethanol is removed in a rotary evaporator.

The solid residue is slurried with water in a blender and theparticulate solid is filtered, washed with water, and air dried. Thecrude product is recrystallized from ethanol, mp 117°-119° C.

C. 4-(6-Methacryloxyhexyloxy)-4'-nitrobiphenyl

4-(6-Hydroxyhexyloxy)-4'-nitrobiphenyl (22 g) is dissolved in 500 ml ofdry dioxane and heated to 45° C. A 14 g quantity of triethylamine isadded, then a solution of 10.5 g of methacryloyl chloride in an equalvolume of dioxane is added dropwise while maintaining the reactionmedium temperature at 45° C.

The reaction medium is stirred at 45° C. for about 24 hours. The dioxanethen is removed under vacuum, and the solid residue is slurried in waterin a blender. The particulate solid is filtered, washed with water, andair dried. The crude monomer product is recrystallized from ethanol, mp53°-56° C.

D. Poly[6-(4-nitrobiphenyloxy)hexyl methacrylate]

The monomer (2 g) is dissolved in 20 ml of degassed benzene in areactor, and 1 mole percent of azodiisobutyronitrile is added to thereaction medium. The reactor is heated at 60° C. for 4 days. During thisperiod, polymer product separates as a solid precipitate from thereaction medium. After the polymerization is completed, the precipitateis recovered and slurried with methanol in a blender. The solid polymeris filtered, washed with methanol, and vacuum dried.

EXAMPLE VII

This Example illustrates a poling procedure for producing a second ordernonlinear optical medium of polysiloxane and liquid crystallinecomponents in accordance with the present invention.

A. Poling Cell Construction

A poling cell is constructed from electrically conductive glass plates,such as Donnelly Mirror PD 5007-7. The glass plates are washed withsulfuric acid, isopropanol, 1-dodecanol, and isopropanol, with adistilled water rinse between each washing step.

The poling cell is a sandwich type cell in which the conductive glasssurfaces are in facing proximity and are separated by a polyimide filmof approximately 25 micrometer thickness. A thin layer of epoxy adhesiveis applied on the surfaces of the polyimide film to hold the glassplates.

After the epoxy is completely cured, the cell is washed with isopropanoland rinsed with distilled water. After drying, the cell is stored in adry box.

B. Filling The Poling Cell

A mixture of polysiloxane of Example I (30 weight %) andpoly[6-(4-nitrobiphenyloxy)hexyl methacrylate]of Example V (70 weight %)is placed in a vacuum oven and maintained in a melt phase at atemperature of about 150° C. for about 4 hours to eliminate entrainedair bubbles from the polymer melt.

The melt phase polymer blend is introduced into the space between theglass plates by charging a drop of the polymer melt to one of theopenings of the poling cell space and placing the cell assembly in avacuum oven maintained at a temperature approximately 10° C. above theclearing temperature of the polymer blend. The cell space fillsgradually by capillary action. The space filling period is about 4 hoursfor a 0.5 cm long space. The polymer melt in the filled cell isbubble-free.

C. Electric Field Induced Orientation

Two lead wires are attached to each of the conductive glass surfacesusing electrically conductive epoxy adhesive. The poling assembly isplaced in a microscope hot stage (Mettler FP-82 with FP-80 CentralProcessor), and the sample is observed with a polarizing microscope(Leitz Ortholux Pol) for alignment.

The microscope is switched into a photodiode (Mettler Photometer No.17517) to record the change of light intensity upon application of anelectric field. The two lead wires are connected to an AC voltageamplifier (Electro-Optic Developments LA10A), which amplifies thevoltage signal from a signal generator (Hewlett-Packard No. 3310B).

The poling cell first is heated to bring the polymer blend to theisotropic phase. The assembly then is cooled at a rate of 0.2° C./min.until the photodiode signal registers an abrupt increase which indicatesthat the melt has undergone a transition into a liquid crystallinephase. The temperature is further lowered by 2° C. and then maintainedat this temperature.

The AC voltage source is set at 500 V, and the frequency is set at 2000Hz. The power to the poling cell is turned on to apply an electric fieldacross the polymer blend sample. The field strength is calculated to beapproximately 2×10⁵ V/cm. About three seconds after the electric fieldis applied, depending on the composition of the polymer blend thephotodiode signal drops close to the baseline, indicating thatorientation development induced by the electric field is completed. Atthis point, the cooling is resumed until the temperature reaches 35° C.,and the poling assembly is disconnected from the power source.

When the poling assembly is removed from the microscope hot stage, byvisual observation the polymer blend in the cell space is transparent.This is an indication that the molecular orientation is uniform andhomogeneous throughout the sample. Orientation of the sample is furtherascertained utilizing a wide angle X-ray diffraction technique, and theHermann's orientation factor of the sample is approximately 0.9.

D. High Field Poling For Symmetry Control

The oriented polymer blend sample is subjected further to a higherelectric field to develop a noncentrosymmetric orientation of nonlinearoptical moieties which are a part of the side chains of the two polymertypes.

The poling cell assembly is heated until it is approximately 5° C. belowthe glass transition temperature of the polymer blend. Then the leadwires of the poling assembly are connected to a DC voltage source (KepcoOPS-3500) and the voltage is turned up slowly until it reaches 2000 V.At this point, the electric field strength across the sample is about8×10⁵ V/cm. The sample is maintained at this field strength level for 10hours, then the sample is cooled and the voltage source is disconnected.A noncentrosymmetrically oriented polymer blend matrix is obtained inthis manner.

From the measurements, there is an indication that a major proportion ofthe nonlinear optical moieties are aligned parallel to the electricfield direction, and the rest are oriented antiparallel to the electricfield direction.

What is claimed is:
 1. An electrooptic light modulator device with anorganic nonlinear optical component comprising a transparent solidmedium of a polymer which is characterized by a recurring structuralunit corresponding to the formula: ##STR25## where R¹ is a hydrocarbylsubstituent containing between about 1-12 carbon atoms; n is an integerof at least 5; and Z' is an electron-donating or electron-withdrawingsubstituent.
 2. An electrooptic light modulator device with an organicnonlinear optical component comprising a transparent solid medium of apolymer which is characterized by a recurring structural unitcorresponding to the formula: ##STR26## where R¹ is a hydrocarbylsubstituent containing between about 1-12 carbon atoms; X' is a C₁ -C₃₀alkyl, alkoxy or alkylthio substituent; Y' is a substituent selectedfrom nitro, cyano and trifluoromethyl groups; and the polymer containsbetween about 5-2000 silicon atoms.
 3. An electrooptic light modulatordevice with an organic nonlinear optical component comprising atransparent solid medium of a polymer which is characterized by arecurring structural unit corresponding to the formula: ##STR27## whereR¹ is a hydrocarbyl substituent containing between about 1-12 carbonatoms; R² and R³ are selected from hydrogen and C₁ -C₃₀ alkyl groups,and R² and R³ taken with the connecting nitrogen atom form aheterocyclic substituent; Y' is a substituent selected from nitro, cyanoand trifluoromethyl groups; and the polymer contains between about5-2000 silicon atoms.
 4. An electrooptic light switch device with anorganic nonlinear optical component comprising a transparent solidmedium of a polymer which is characterized by a recurring structuralunit corresponding to the formula: ##STR28## where R¹ is a hydrocarbylsubstituent containing between about 1-12 carbon atoms; n is an integerof at least 5; and Z' is an electron-donating or electron-withdrawingsubstituent.
 5. An electrooptic light switch device with an organicnonlinear optical component comprising a transparent solid medium of apolymer which is characterized by a recurring structural unitcorresponding to the formula: ##STR29## where R¹ is a hydrocarbylsubstituent containing between about 1-12 carbon atoms; X' is a C₁ -C₃₀alkyl, alkoxy or alkythio substituent; Y' is a substituent selected fromnitro, cyano and trifluoromethyl groups; and the polymer containsbetween about 5-2000 silicon atoms.
 6. An electrooptic light switchdevice with an organic nonlinear optical component comprising atransparent solid medium of a polymer which is characterized by arecurring structural unit corresponding to the formula: ##STR30## whereR¹ is a hydrocarbyl substituent containing between about 1-12 carbonatoms; R² and R³ are selected from hydrogen and C₁ -C₃₀ alkyl groups,and R² and R³ taken with the connecting nitrogen atom form aheterocyclic substituent; Y' is a substituent selected from nitro, cyanoand trifluoromethyl groups; and the polymer contains between about5-2000 silicon atoms.